CVE-2021-33818
Attackers can use slowhttptest tool to send incomplete HTTP request, which could make server keep waiting for the packet to finish the connection, until its resource exhausted.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.93%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
An issue was discovered in UniFi Protect G3 FLEX Camera Version UVC.v4.30.0.67. Attackers can use slowhttptest tool to send incomplete HTTP request, which could make server keep waiting for the packet to finish the connection, until its resource exhausted. Then the web server is denial-of-service.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 1.93% probability · 80th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-400
- Affected
- ui/camera g3 flex firmware
- Source
- cve@mitre.org
EPSS 1.9% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://github.com/Jian-Xian/CVE-POC/blob/master/CVE-2021-33818.mdExploit, Third Party Advisory
- https://github.com/shekyan/slowhttptestThird Party Advisory
- https://store.ui.com/collections/unifi-protect-cameras/products/unifi-video-g3-flex-cameraProduct, Vendor Advisory
- https://github.com/Jian-Xian/CVE-POC/blob/master/CVE-2021-33818.mdExploit, Third Party Advisory
- https://github.com/shekyan/slowhttptestThird Party Advisory
- https://store.ui.com/collections/unifi-protect-cameras/products/unifi-video-g3-flex-cameraProduct, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.